American Chemical Society
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Synthesis and Structural Analysis of the First Nanosized Platinum−Gold Carbonyl/Phosphine Cluster, Pt13[Au2(PPh3)2]2(CO)10(PPh3)4, Containing a Pt-Centered [Ph3PAu−AuPPh3]-Capped Icosahedral Pt12 Cage

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journal contribution
posted on 2005-12-26, 00:00 authored by Namal de Silva, Lawrence F. Dahl
The preparation and molecular structure of the initial nanosized platinum−gold carbonyl cluster, Pt13[Au2(PPh3)2]2(CO)10(PPh3)4 (1), are described. A comparative analysis reveals its pseudo-D2h geometry, consisting of a centered Pt13 icosahedron encapsulated by two centrosymmetrically related bidentate [Ph3PAu−AuPPh3]-capped ligands along with 4 PR3 and 10 CO ligands, to be remarkably similar to that of the previously reported Pt172-CO)4(CO)8(PEt3)8 (2). Reformulation of 2 as Pt13[(PtPEt3)22-CO)]2(CO)10(PEt3)4 emphasizes the steric/electronic resemblance of the bulky-sized bidentate [Ph3PAu−AuPPh3] and [(PtPEt3)22-CO)] capping ligands in 1 and 2, respectively, as well as their identical electron counts of 162 cluster valence electrons for a centered Pt13 icosahedron. We hypothesize that analogous steric effects of their ligand polyhedra in 1 and 2 play a crucial role along with electronic effects in the formation and stabilization of these two nanosized clusters that contain an otherwise unknown centered icosahedron of platinum atoms.